Project Summary/Abstract Functional cures of HIV have been documented, but rebound of plasma HIV RNA from the ?Mississippi baby?6 and Boston bone marrow transplant recipients7 from latent reservoirs after post-ART aviremia confirms HIV reservoirs are a significant barrier to a cure. This proposal will examine one model of an immune mediated mechanism that replenishes HIV tissue reservoirs, i.e. cellular proliferation. We will determine whether antigen (Ag)-specific responses to recurrent herpes simplex viruses (HSV) replenish HIV reservoirs by increasing HIV DNA concentrations and HIV env diversity via cellular proliferation and recruitment of Treg and Ag-specific CD4+ T cells to sites of recurrence and to the surrounding tissues. The role of Ag-specific responses to chronic HSV, which are prevalent in HIV infected subjects (~45-90%), has not been studied in humans during suppressive antiretroviral therapy (ART). HSV-2 episodically reactivates in tissues throughout subject?s life even during suppressive ART for HIV.[5-7] We will recruit 40 HIV(+) HSV-2(+) subjects that are currently receiving suppressive combination antiretroviral therapy (ART, <30 copies/mL) for HIV from the University of Washington Virology Research Clinic (UW-VRC) in Seattle, Washington. All subjects will be instructed to collect 28-days of anogenital samples that will be assayed using HSV real-time PCR to generate an HSV shedding rate. Women will also collect cervical secretions using the Instead Softcup? to determine whether subclinical HSV shedding at the uterine cervix induces HIV expression. Subjects will return to clinic to have blood, anogenital, cervical (women) or rectal (men) biopsies collected. HIV(+) HSV(+) subjects will receive four months of valacyclovir 500 mg daily to suppress HSV recurrences. After four months, subjects will return to the clinic for collection of blood, anogenital and cervical or rectal biopsies. Specimens will be assessed for HIV DNA concentrations, HIV env diversity, and the frequency of CD4+ Ag-specific T helper and Treg cells associated with HIV DNA and RNA. Any HSV clinical recurrences after stopping Val throughout one year of follow-up will be biopsied. HSV shedding/recurrence will be used in a linear regression model as the predictor for the following outcomes: HIV DNA concentrations, HIV env diversity, and the frequency of CD4+ Treg and Ag-specific T cells. Comparisons within HIV(+) HSV(+) subjects that have recurrences will be performed using a paired Wilcoxon sign rank test. Understanding whether cellular proliferation, as part of the normal immune response to herpes recurrences, replenishes or promotes the seeding of HIV tissue reservoirs (e.g. uterine cervix) is critical to our understanding immune mechanisms that could pose a barrier to HIV eradication. These studies may suggest therapeutic interventions to improve the health of HIV/HSV co-infected individuals and inform whether the immune response to chronic viral infection should be considered as we develop HIV ?cure? strategies.